# 字符串每5个字符插入一个','
# 2021-8-4
# by: Nasa

zfc1= 'abcdefghijklmnopqrstuvwxyz'
j=0
zfc2=''
for i in zfc1:
    j=j+1
    if j%5==0:
        zfc2=zfc2+i+','
    else:
        zfc2=zfc2+i
print(zfc2)